KAGRA Logbook

IOO (IMC)

keiko.kokeyama - 2:10 Thursday 26 March 2020 (13824)

IMC drift control

[Nakano, Kokeyama]

Following loops were tested and worked ok. UGF 0.1Hz or below. The sensor/actuator assingments were decided by measuring sensing matrices quickly. They haven't automated or anything yet as I need the downstream ifo was fixed to fix the DC offsets.

DOF1: MCE TRANS 1 => MCO (P only. Y couldn't be closed because of couplings)
DOF2: IMMT1 TRANS => MCE (both P,Y)
These sensors are sensitive both for MCO and MCE so there are couplings especially in Y. So it might not very ideal, but seemed OK to freeze spot positions.

DOF3 will be WFS. WFSs sees only input pointing 2 (IP2). But IP2 (and IP1) are working on the edge of the DAC range and doesn't have spare for feedback. I need to go inside the PSL room to center the nominal PZT offset, which is not a great idea at this timing,

Comments to this report:

keiko.kokeyama - 3:44 Friday 27 March 2020 (13845)

DOF1 P, DOF2 P and Y were implemented in imc guardian. Whe IMC_LOCKED is requested, the QPD loops work. Since I am worried if the actuator ranges of the MC sus are enough or not, I decided to make the guardian to watch the MC sus actuator outputs and if any of them becomes close to 10000 cts, the guardian softly turns off the QPD loops and it goes to LSC_LOCKED (without QPD loops).

Because I did not change IO guardian yet, currently IMC_LOCKED is manually requested for a long term (several hours) test. IO guardian is PSL_LOCKED. If the loops seem good we can include into IO guardian.

Noise performance or actual ugfs haven't measured yet.

If the MC lock is broken, please use IO guardian as usual. You might have to intentionally go 'DOWN' to recover the mc.

keiko.kokeyama - 22:50 Monday 30 March 2020 (13908)

I noticed that the QPD loops are disturbed and they go crazy when PRFPMI is RF locked presumably because of scattered lights. The TRANS POWER goes drastically down, as pointed as allows in the attached plots.

Also, because it is a DC control, while loops are closed QPD positions are fixed but the TRANS power drift too much.

I will do something during ER.

* I observed something strange on IO guardian. If it says an error "permission denied," please jsut click "LOAD."

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